Catalytic growth of carbon nanoballs with Co encapsulation from CH4 decomposition: MoOx-promoted shrinking of the carbon nanoball size.

Compared with Co/MgO catalysts with high Co loading and without Mo addition, the addition of Mo oxide to low Co-loading Co/MgO catalysts can promote the growth of smaller sized Co-encapsulated carbon nanoballs (CNBs) by the decomposition of methane. The catalysts were carefully studied by X-ray photoelectronspectroscopy (XPS), X-ray diffraction (XRD), and temperature-programmed reduction (TPR). The promotion effect of Mo on the increase in the carbon deposition and the reduction in the CNB size, as well as the relation between the carbon product and metal particle size, are discussed.